Kyle - excellent find, I have confirmed that this was the cause of my issue, too. Thank you!
I had taken a quick glance at /etc/apcupsd/apcupsd.conf when I was failing to see communication working with my UPS, as I saw the expected lines to configure apcupsd for USB mode I had assumed there was a deeper problem and never got around to looking at it again. To confirm, the config contains these lines by default: UPSTYPE usb DEVICE /dev/ttyS0 I commented out the 'DEVICE' line like so: UPSTYPE usb #DEVICE /dev/ttyS0 Then I restarted the service with: # sudo systemctl restart apcupsd I no longer see the IRQ messages in dmesg output. Great! Does this apply to everyone else that has encountered this, I wonder? -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1781016 Title: Slow flood of do_IRQ: No irq for vector Status in linux package in Ubuntu: Incomplete Bug description: Every few seconds I get something like this in my dmesg: [44984.933221] do_IRQ: 1.34 No irq handler for vector [44986.933976] do_IRQ: 1.34 No irq handler for vector [44991.935614] do_IRQ: 1.34 No irq handler for vector [45004.938590] do_IRQ: 1.34 No irq handler for vector [45005.939002] do_IRQ: 4.34 No irq handler for vector [45034.949161] do_IRQ: 4.34 No irq handler for vector [45051.954569] do_IRQ: 4.34 No irq handler for vector [45058.956019] do_IRQ: 4.34 No irq handler for vector [45062.957727] do_IRQ: 4.34 No irq handler for vector [45063.958204] do_IRQ: 4.34 No irq handler for vector [45073.961103] do_IRQ: 4.34 No irq handler for vector The numbers vary. Some examples are 4.34, 4.36, 1.34, 0.33, 6.34, 7.33, 5.37. Eventually dmesg's ring buffer is full and my entire log is just messages like above with varying #.## numbers. I researched it and tried disabling irqbalance. It had no effect, the messages continued. The system is a Ryzen 2700X with B350 chipset on Asus Prime B350-PLUS. I have 64GB of Kingston DDR4-2400 ECC memory and Samsung 960 PRO M.2 NVMe SSD, and an Intel I350-T4 quad port gigabit NIC. This issue never occurred before installing 18.03 on the same hardware. No overclocking whatsoever has ever been done to this machine. Also, I had to disable selective suspend on USB in this version to prevent major USB issues, which was not required in 17.10, that might be related. My system seems stable, but spurious IRQs can't be good. I'd like to resolve this if possible. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: linux-image-4.15.0-26-generic 4.15.0-26.28 ProcVersionSignature: Ubuntu 4.15.0-26.28-generic 4.15.18 Uname: Linux 4.15.0-26-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.20.9-0ubuntu7.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: gdm 2145 F.... pulseaudio doug 3736 F.... pulseaudio /dev/snd/controlC1: gdm 2145 F.... pulseaudio doug 3736 F.... pulseaudio Date: Tue Jul 10 12:49:00 2018 HibernationDevice: InstallationDate: Installed on 2017-06-26 (379 days ago) InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) MachineType: System manufacturer System Product Name ProcEnviron: LANGUAGE=en_CA:en TERM=xterm-256color PATH=(custom, no user) LANG=en_CA.UTF-8 SHELL=/bin/bash ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-26-generic root=UUID=53446747-0814-48f7-b7c4-7fd7d7234d83 ro video=vesa:off vga=normal video=efifb:off usbcore.autosuspend=-1 usbhid.quirks=0x1e71:0x170e:0x4 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not accessible: Permission denied No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-4.15.0-26-generic N/A linux-backports-modules-4.15.0-26-generic N/A linux-firmware 1.173.1 RfKill: SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/19/2018 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 4011 dmi.board.asset.tag: Default string dmi.board.name: PRIME B350-PLUS dmi.board.vendor: ASUSTeK COMPUTER INC. dmi.board.version: Rev X.0x dmi.chassis.asset.tag: Default string dmi.chassis.type: 3 dmi.chassis.vendor: Default string dmi.chassis.version: Default string dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr4011:bd04/19/2018:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnPRIMEB350-PLUS:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring: dmi.product.family: To be filled by O.E.M. dmi.product.name: System Product Name dmi.product.version: System Version dmi.sys.vendor: System manufacturer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1781016/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp